1. Field of the Invention
The invention relates to an apparatus for lifting and conveying a signature fed on a wedge-shaped saddle or saddle conveyor, which signature lies with the inner side of its back on the vertex of the saddle. The apparatus comprises an upwardly and downwardly movable lifting comb which has comb tongues with upper edges for moving below the inner side of the signature back and which serves to lift the signature from the saddle to a transfer station, where it is transferred from the lifting comb to a conveyor which has at least two conveyor elements with endless conveyor surfaces lying side by side to form a clamping gap for the signature and being movably mounted for movement along endless paths in order to advance the signature for further processing. The apparatus further comprises drive members for driving the lifting comb and at least one of the two conveyor elements.
2. Description of the Prior Art
The term "signature" as used herein shall mean a booklet and designates superposed or nested foils or sheets, preferably paper sheets, which are folded together about a common fold line, said fold line defining a signature back or backbone. The margin of the signature adjacent to this signature back will be referred to in the following as "back margin". The foils or sheets constituting the signature can be stitched together by staples, or glued together at the signature back. However, they may also be arranged in loose contact with each other. In the known apparatus of the above-mentioned type, conveyor elements are used which consist of rollers and/or conveyor belts lying side by side so as to define a clamping gap. It is to this clamping gap that the signature lifted from the saddle is fed by the comb tongues in the known apparatus. It has however to be taken into consideration that the upwardly and downwardly moving lifting comb transfers the signature to the clamping gap in its upper dead-center position. The lifting movement of the lifting comb must therefore have been delayed to zero by the time the signature is introduced into the clamping gap. In view of the high demands on the output of apparatus of the above-mentioned type, this will result in accelerations and delays of the order of magnitude of a multiple of the acceleration by gravity. Thus it cannot be avoided with certainty in the known apparatus of the above-mentioned type that due to the considerable delay in the movement of the lifting comb, the signature will come off the upper edges of the comb tongues immediately in front of the clamping gap and reach the clamping gap prematurely and in an inaccurate position. For this reason it is known that additional aligning means have been provided for the further handling of the signatures, which exactly re-position the signature before it is further processed, for example trimmed.
It is the object of the invention to provide an apparatus for lifting and advancing a signature fed on a wedge-shaped saddle, wherein the signature is introduced into the clamping gap in an exactly defined position so that additional aligning is not necessary.